Preparation of Li₂S-FeS₂ Composite Electrode Materials and their Electrochemical Properties

Abstract

Li₂S-FeS₂ composite positive electrode materials were prepared for improving the discharge capacity of the all-solid-state In/Li₂S cells via the electrical conductivity enhancement of Li₂S. The electrochemical tests demonstrated that the In/Li₂S-FeS₂ (Li₂S : FeS₂ = 3 : 7 wt) cells showed relatively higher discharge capacity (ca. 180 mAh • g⁻¹, normalized by the cathode weight) than that of the In/Li₂S-C cells (ca. 140 mAh • g⁻¹), due to the increased fraction of the active materials in the cathodes. The ex-situ XRD and S K-edge XAFS results indicated that the In/Li₂S- FeS₂ cells showed similar electrochemical reaction to that of the Li/Li₂S-FeS₂ cells with liquid electrolytes during charge, but did not proceed to form Li₂S and Fe during discharge. Such difference was due to the limited amounts of Li ions supplied from the lithiated-In anode during discharge for the In/Li₂S-FeS₂ cells.